<!DOCTYPE html>
<style>
#mask {
  width: 200px;
  height: 200px;
  overflow: hidden;
  border-radius: 10px;
  border: 4px solid red;
  background-color: grey;
  transform-style: preserve-3d;
}

.scale-seam {
  position: relative;
  left: 100px;
  transform-origin: 0 0;
  transform: scale(2, 1) rotateY(30deg) rotateX(30deg) rotateZ(30deg);
  display: inline-block;
}

.content {
  width: 500px;
  height: 500px;
  filter: blur(15px);
}
</style>
<div class="scale-seam">
  <div id="mask">
    <div class="content" style="left: 0;top: 0;background: black;"></div>
  </div>
</div>
